The present invention pertains to an elongate rotary tool such as, for example, a drill, an endmill, a tap, a burr, a countersink, a hob, or a reamer, comprising at one end a shank adopted to be secured (e.g., by a chuck) to a machine tool and at another end a elongated body, which is optionally fluted. The elongated body may be comprised of multiple cutting edges, such as for example, a first cutting edge at the juncture of a first flank and a face, which optionally defines and transitions to at least a portion of a flute, and a second cutting edge at the juncture of a second flank and the face, which transitions from the first cutting edge at a common corner. The elongate rotary tool is for the machining of workpiece materials. For example and in the case of a drill, such an elongate rotary tool has been typically used to drill both through and blind holes in workpiece materials. For example and in the case of an end mill, such an elongate rotary tool has been typically used to mill workpiece materials.
For the most part when made from a cermet, elongate rotary tools are comprised of tungsten carbide cermets (WC-cermets), also known as cobalt cemented tungsten carbide or WC--Co . Here, a cobalt binder (Co-binder) cements tungsten carbide particles together. Although WC-cermets have achieved successful results as elongate rotary tools, there are some drawbacks.
One drawback is that up to about 45 percent of the world's primary cobalt production is located in politically unstable regions (e.g., political regions that have experienced either armed or peaceful revolutions in the past decade and could still experience additional revolutions). About 15 percent of the world's annual primary cobalt market is used in the manufacture of hard materials including WC-cermets. About 26 percent of the world's annual primary cobalt market is used in the manufacture of superalloys developed for advanced aircraft turbine engines--a factor contributing to cobalt being designated a strategic material. These factors not only contribute to the high cost of cobalt but also explain cobalt's erratic cost fluctuations. Consequently, cobalt has been relatively expensive, which, in turn, has raised the cost of WC-cermet elongate rotary tools. Such an increase in the cost of elongate rotary tools has been an undesirable consequence of the use of a Co-binder for elongate rotary tools. Therefore, it would be desirable to reduce cobalt from the binder of cermets.
Furthermore, because of the principal locations of the largest cobalt reserves, there remains the potential that the supply of cobalt could be interrupted due to any one of a number of causes. The unavailability of cobalt would, of course, be an undesirable occurrence.
Elongate rotary tools may operate in environments that are corrosive. While WC-cermets having a Co-binder have been adequate in such corrosive environments, the development of elongate rotary tools that have improved corrosion resistance without losing any of the machining performance remains an objective.
While the use of WC-cermets having a Co-binder for elongate rotary tools has been successful, there remains a need to provide an elongate rotary tool that does not have the drawbacks, i.e., cost and the potential for unavailability, inherent with the use of cobalt set forth above. There also remains a need to develop an elongate rotary tool for use in corrosive environments that possess improved corrosion resistance without losing any of the cutting performance characteristics of WC-cermets having a Co-binder.